The clinical utility of a symptom index for ovarian cancer depends on precisely how it is used and how index-positive women are managed, indicate the results of a recent study.
To determine the effectiveness of symptom indices designed for the early detection of ovarian cancer, researchers from Queen Mary University of London in the United Kingdom analyzed data from 194 women 50 to 79 years with newly diagnosed ovarian cancer and 268 control subjects who had been screened for the disease. Information on symptoms and their onset dates were obtained by questionnaire, telephone interview, and notes taken by general practitioners (GPs). Data from the questionnaires and GP notes were used to derive two new symptom indices, and sensitivity and specificity for these new indices and the previously reported Goff index, which uses questionnaire data, were calculated for two 12-month periods preceding diagnosis (0-11 and 3-14 months) for all three data sources.
For each data source and period, the two new indices were similar both qualitatively (symptoms included) and quantitatively (sensitivity and specificity) to the Goff index. The sensitivity of the symptoms were stronger in late-stage disease than in early-stage disease: Sensitivity decreased for all indices and all data sources when symptoms that started within 3 months before diagnosis were excluded.
In addition, the specificity of all indices was consistently lower for telephone interviews than for questionnaires and GP notes.
These outcomes demonstrate that previous estimates of index performance had been overly optimistic because they did not take into account the time required to make a diagnosis on the basis of testing in response to symptoms. Moreover, the specificity of a symptom index is lower when based on a telephone interview rather than a questionnaire or GP notes.
The investigators concluded that there is little to gain from deriving new symptom indices, and suggest that while a symptom index could advance the diagnosis of ovarian cancer, the benefits of such are greatly overemphasized given that most symptoms emerge within 3 months before diagnosis (J Natl Cancer Inst. 2012;104:114-124).